Evaluation of the potential of surface enhancement Raman spectroscopy for detection of tricyclic psychotropic drugs. Case studies on imipramine and its metabolite

Abstract

The potential use of surface Raman enhanced spectroscopy (SERS) for confirmatory identification and the semi-quantitative analysis of selected tricyclic antidepressants (TCAs) is examined utilizing a conventional silver colloid. Raman and SERS spectra of aqueous solutions of imipramine (Imi) and its metabolite, desipramine (Des), were recorded as the function of concentration using NIR excitation. A good linear correlation is observed for the dependence of the SERS signal at 684 cm⁻¹ (R² = 0.9997) on Imi concentration over the range of 0.75–7.5 μM. The limit of detection of imipramine in the silver colloidal solution is 0.98 μM. SERS spectra of Imi and Des were also recorded for blood plasma samples without prior purification as well as after the use of standard solid phase extraction. All spectra show the characteristic spectral profile of the molecules and moreover, stronger signal enhancement is observed for Imi in the “raw” samples as opposed to Imi extracted from a biological matrix.